One of the big concerns any time a beloved television series makes it to the big screen is that the film version won’t do justice to the original, but fans of Disney Channel’s Phineas and Ferb can probably put that worry to rest. It was announced earlier this year that the animated show would be getting a theatrical movie in 2013, and we’ve now learned that Disney has tapped Toy Story 3 and Little Miss Sunshine writer Michael Arndt to write a draft of the script. More details after the jump.